We are testing the efficacy of methadone temporary support, a strictly time limited (1 year) program for stabilizing heroin addicts on long-acting methadone (levo-alpha-acetylmethadol, LAAM), then tapering dosage and eventually discontinuing the opiate, with intensive supportive services throughout the duration of the program, and during aftercare. As part of this research we are studying plasma levels of LAAM, to compare the efficacy of a tricyclic antidepressant with an established medication (diazepam) in the management of the withdrawal syndrome, and plan to test the efficacy of the antagonist, naltrexone, in preventing or reducing the frequency of relapse during the abstinence phase after withdrawal.